Electric current rectifier control



Aug. 28, 1934. A. GAUDENZ] ET AL ELECTRIC CURRENT RECTIFIER CONTROLFiled Dec. 1, 1951 Patented Aug. 28, 1934 raisin ATEN? ELECTRIC CUnnEN-rRECTIFIER CONTROL Arthur Gaudenzi,

Baden,

and Ernst Kobe],

Application December 1, 1931, Serial No. 578,242 In Germany December 1,1930 Claims.

This invention relates to improvements in electric current rectifyingsystems utilizing a rectifier of the metallic vapor arcing type and moreparticularly to the provision in such systems of improved surgedischarges.

When potential surges occur in an electric current rectifying system,one of the usual results is the occurrence of backfires which may causeserious damage to the system. It is, therefore, desirable that suchsurges be discharged by means other than the portions of the rectifierstructure involved in the rectifying action and before reaching amagnitude such as would cause a backfire. Such means for dischargingsurges may include a spark, or arc, gap in which one of the'polescomprises a suitable portion of the rectifier structure and the otherpole of which is an electrode extending into the rectifier into the zoneof the greatest vapor density and the greatest accessibility to metallicions. The resistance of such gap to the dischargeof surges is thereforelow relative to the resistance to such discharge by way of therectifying anodes. The

2 immediate breaking down of the gap is thus assured. If, therefore, asurge potential appears at any of the rectifying anodes, particularlywhen such anodes are operating, the spark gap acts immediately andthesurge potential is discharged in such time asto prevent establishment ofa backfire. The transformer supplying the rectifier is most frequentlythe source of such excess potentials for the reason that it permitspotentials to build up therein. 7

It is, therefore, among the objects of the present invention to providemeans for discharging surges in an electric current rectifying systememploying a rectifier of the metallic vapor type in such manner as notto affect the anodes of the rectifier employed in the rectifyingaction.

Another object cf the invention is to provide means for dischargingsurges in an electric current rectifyingsystem employing a rectifier ofthe metallic vapor type in which the discharge will take place beforesuch conditions can arise in the rectifier as will cause a'backfiringaction therein. Another object of the invention is to provide a specialpath for the discharge of excess potentials occurring in anelectriccurrent rectifying system.

Another object of the invention is to provide an electric currentrectifying system having a path for the discharge of excess potentialsoccurring in such system which path will more readily permit dischargeof such potentials than the anodes of an electric current rectifyingstructure of the metallic vapor arcing type.

Objects and advantages, other than those above set forth, will beapparent from the following description when read in connection with theac- 6O companying drawing in which:

Figure l diagrammatically illustrates an electric current rectifyingsystem util 'ng an electric current rectifier of the metallic vaporarcing type in which means are provided for discharging abnormalpotentials from the system by the provision of a discharge path notinvolving the anodes of the rectifier; and

Figs. 2, 3, i and 5, illustrate modified embodiments of the surgedischarging path structure in an electric current rectifying system ofthe character above mentioned.

Referring more particularly to the drawing by characters of reference,the reference numeral 6 designates an alternating o i nt supply lineconnected with the primary winding 7 of a transformer. The secondarywi... o the transformer are connected to provide a neutral point and theterminals of the windings are each connected through a reactance 9 oflow capacitance with one of a plurality of main anodes 11 of a rectifierstructure of the metallic vapor arcing type which includes a container12 and a pool of vaporizable material 13 such as mercury, insulated fromthe container and forming a cathode. The anodes and the cathode areenclosed within the container and are insulated therefrom. The anodes 11are partially enclosed within arc guides 14; which are suspendedthereabout in insulated relation therewith. A conductor 16 connectedwiththe neutral point of the secondary windings 8 and a conductor 1'?connected with the cathode 13 together with a load, herein representedby a resistance 18, form the circuit to which direct current is suppliedfrom the rectifier.

Auxiliary electrodes 21 extend into the container 12 in insulatedrelation therewith into a Zone of a great vapor density and a greatnumber of metallic ions within the rectifier to establish a relativelylow resistance discharge path for such electrodes and to assure thebreaking down of the gap between the electrodes and the cathode. Each ofthe electrodes is connected with one of the anode connections with thetransformer secondary windings 8 through an ohmic resistance 22 whichlimits the current which may flow through the auxiliary electrodes. Theauxiliary electrodes are thus arranged to form a path with the cathode13 for the ready discharge of abnormal potentials from the connectionsbetween 11.0

the main anodes and the transformer secondary winding. The auxiliaryelectrodes carry a very small amount of current as determined by theresistance 22 and the voltage drop between the electrode and the cathodeduring the time the arc is flowing from the anode, to which suchelectrode is connected, and the cathode. The discharge of surges beingdetermined by the capacitance and the reactance in the circuit and theauxiliary electrode connection having only an ohmic re sistance whereasthe anode connection has a reactance therein, any surges appearing atthe terminal of a transformer secondary coil will be discharged by wayof the auxiliary electrode rather than by way of the anode.

The continuous passage of a small amount of a current through theauxiliary electrode, however, introduces a loss into the rectifyingsystem which is undesirable. creased by the use of a second ohmicresistance 23, preferably of higher value than resistance 22, in serieswith the first resistance 22 as shown in Fig. 2. The resistance 23 isbridged by means 24, such as a glow tube permitting the flow of currenttherethrough as soon as a predetermined voltage has been reached. Theoccurrence of excess voltages therefore causes the tube to break downupon the occurrence of a surge which shortcircuits resistance 23. Theuse of two resistances in the auxiliary electrode connection with meansfor short-circuiting one of such resistances also increases thesensitivity of the arc gap.

The resistances 22 and 23 may be replaced b condensers 26 and 27, asshown in Fig. 3, which operate to permit the passage of currenttherethrough upon the occurrence of excess potentials whereupon tube 24will break down to permit the discharge of the excess potentials by wayof electrodes 21.

If a plurality of electrodes are used, each of which is arrangedadjacent to a main anode, the circuit conductors for all of theauxiliary electrodes may be extended into the rectifier containerthrough a single insulating bushing.

The structure of a rectifying system may be fur ther simplified by usingonly one auxiliary electrode for a number of anodes as shown in Fig. 4in which the electrode 21 is shown connected between the terminals oftwo of the transformer secondary winding coils through resistances 31and 32 and glow tubes 33 and 34.

It will be understood that the same electrode may be connected with anynumber of anodes merely by the use of additional resistances and glowtubes in a manner similar to that shown in Fig. 4. The resistances 31and 32 limit the current which may flow through the auxiliary electrode.The voltage at which the glow tube will permit passage of current ispreferably less than the maximum normal voltage of the transformer andthe tubes may be such as to permit passage of current there-through inonly one direction.

. The resistances and glow tubes shown in the connection of theauxiliary electrodes with the "j anodes in theembodiment of theinvention according to Fig. 4 of the drawing may be replaced bycondensers .36 and .37 as shown in Fig. 5. A number of condensers may bearranged in the connection of the electrode with each of the anodes, andone of which condensers may be bridged by a glow tube as shown in Fig.3.

The present invention provides a path for the discharge of surges otherthan by way of the .main anodes, which path will permit the discharge ofsurges more readily than by way of the anodes.

Such loss may be de- Such result is due particularly to the absence ofcapacitance and reactance in the auxiliary electrode circuit and to thearrangement of the electrode in a zone of a great vapor density withinthe tank. The resistance to the discharge of the surges may be decreasedby employing material for the auxiliary electrode which will permitheating thereof to about 2000 C. or above, or by coating the electrodewith a material such as will increase the electron emission thereof.

Although but a few embodiments of the present invention have beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or the scope of the appendedclaims.

The invention claimed is: a

1. In an' electric current rectifying system, an alternating currentsupply line, an electric current rectifier of the metallic vapor typehaving anodes subject to surges, a transformer connecting the anodes ofsaid'rectifiw with'sa'id supply line, a reactance arranged in theconnection of each of the anodes with said transformer, an auxiliaryelectrode connected with each of the anodes of said rectifier betweenthe transformer and the reactance and extending into a zone of greatvapor density within said rectifier, and means connecting saidelectrodes with the corresponding anodes of said rectifier to cause'discharge of the surges therefrom more readily through said electrode thanthrough the anodes.

2. In an electric current rectifying system, an alternating currentsupply line, an electric current rectifier of the metallic vapor typehaving anodes and a cathode forming a path for the discharge of surges,a transformer connecting the anodes of said rectifier with said .supplyline, a reactance arranged in the connection of each of the anodes withsaid transformer, an auxiliary electrodeconnected with each ofthe anodesof said rectifier between the transformer and the reactance andextending into a zone of great vapor density within said rectifien'andohmic resistances included in the connections of said electrodes withthe corresponding anodes to cause discharge of the surges from theconnections of the anodes with said transformer before discharge of suchsurges through the anodes.

3. In an electric current rectifying system, an alternating. currentsupply line, an electric current rectifier of the metallic vapor typehaving anodes and a cathode forming a path for the discharge of surges,a transformer connecting the anodes of said rectifier with said supplyline, a

reactance arranged in the connection of each of the anodes with saidtransformenan auxiliary.

electrode connected with each of the anodes of said rectifier betweenthe transformer and the reactance and extending into a zone of agreatvapor density within said rectifier, a plurality of ohmic resistancesincluded in theconnection of each of said electrodes with thecorresponding anodes to cause discharge of the surges through v analternating current supply line, an electric current rectifier of themetallic vapor type having anodes and a cathode forming a path for thedischarge of surges, a transformer connecting the anodes of saidrectifier with said supply line,

,a reactance arranged in the connection of each of the anodes with saidtransformer, an auxiliary electrode connected with each of the anodes ofsaid rectifier between the transformer and the reactance and extendinginto the zone of relatively great vapor density within said rectifier, aplurality of condensers included in the connection of each of saidelectrodes with the corresponding anodes to cause discharge of surgesthrough said electrode before discharge of such surges through theanodes, and means adapted to permit the flow of current therethroughupon the application thereto of a predetermined voltage, said meansbeing arranged to short-circuit one of each of said plurality ofcondensers, said condenser and said means forming a path for morereadily discharging surges than the path including said anodes.

5. In an electric current rectifying system, an alternating currentsupply line, an electric current rectifier of the metallic vapor typehaving anodes and a cathode forming a path for the discharge ofpotential surges, a transformer connecting the anodes of said rectifierwith said supply line, a reactance arranged in the connection of each ofthe anodes with said transformer, an auxiliary electrode connected witheach of the anodes of said rectifier between the trans former and thereactance and extending into a zone of a great vapor density within saidrectifier, ohmic resistances included in the said connection of each ofthe electrodes with the corresponding anodes to cause discharge ofpotential surges through said electrodes before discharge of such surgesthrough the anodes, and glow tubes adapted to permit the fiow of currenttherethrough upon the application thereto of a predetermined voltage,said tubes being connected in series with said resistances and formingtherewith and with said electrodes a path for more readily dischargingsurges than the path including the anodes.

6. In an electric current rectifying system, an alternating currentsupply line, an electric current rectifier of the metallic vapor typehaving anodes and a cathode forming a path for the discharge ofpotential surges, a transformer connecting the anodes of said rectifierwith said supply line, a reactance arranged in the connection of each ofthe anodes of said rectifier, an auxiliary electrode arranged withinsaid rectifier in a zone of a great vapor density therein, ohmicresistances severally connected with said anodes, and glow tubesconnecting said resistances with the said electrode, said tubes beingadapted to permit the flow of current therethrough upon the applicationthereto of a predetermined voltage, said resistance and said tubesforming a path more readily operative to discharge surges occurring inthe system than the path including the anodes.

'7. In a system of the character described, an electric currentrectifier of the vaporous type comprising an anode subject to impressionof potential surges thereon, means comprising an electrode connectedwith said anode extending into a zone of relatively great vapor densitywithin said rectifier, and means connected with said anode operable todivert discharge of said surges by way of said electrode.

8. In a system of the character described, an electric current rectifierof the vaporous type comprising a plurality of anodes subject to theimpression of potential surges thereon, means comprising an electrodeconnected with said anodes and extending into a zone of relatively greatvapor density within said rectifier, and 11 means connected with saidanodes operable to divert discharge of said surges by way of saidelectrode.

9. In a system of the character described, an electric current rectifierof the vaporous type comprising a plurality of anodes subject to theimpression of potential surges thereon, means comprising an electrodeconnected with said anodes, means included in the connections betweensaid anodes and electrode operable to prevent flow of electric energy byway of said electrode at voltages below a predetermined value, and meansconnected with said anodes operable to divert discharge of said surgesby way of said electrode when the potentials thereof exceed saidpredetermined Value.

10. In a system of the character described, an electric currentrectifier of the vaporous type comprising a plurality of anodes subjectto the impression of potential surges thereon, means comprising anelectrode connected with said anodes and extending into said rectifier,means comprising glow tubes included in the connections between saidanodes and said electrode operable to prevent flow of electric energy byway of said electrode at voltages below a predetermined value, and meansconnected with said anodes operable to cause discharge of said surges byway of said electrode when the potentials thereon exceed saidpredetermined value.

ARTHUR GAUDENZI. ERNST KOBEL.

